Wrapped pencil-shaped articles and method of making same



Feb. 14, 1956 .1. J. CLANCY ET AL 2,734,339

WRAPPED PENCIL-SHAPED ARTICLES AND METHOD OF MAKING S'AME Fil ed Oct. 19, 1951 giL i F/& 2 H66 F/c; 4 F/G 5 INVENTORS JOHN J. Cum/av Dav/0 M LOI/E/P/A/G' United States Patent WRAPPED PENCIL-SHAPED ARTICLES METHOD OF MAKING SAME John ,J. Clancy, Westwood, and David W.:Lovering, Needham, Mass., assignors to Arthur D. Little, Inc., Cambridge, Mass., a corporation of Massachusetts Application October 19, 1951, Serial No. 252,172

6 Claims. (01. 154-83) This invention relates to the manufacture of wrapped pencils and pencil-like articles, "and more particularly to the manufacture of pencils and pencil-like articles whose sheaths are prepared from paper.

Because the supply of cedar wood suitable for pencil manufacturers is no longer-obtainable in unlimited quantities, and is becoming increasingly expensive, attention has been directed to the manufacture ,of pencils bysheathing the pencil lead with alternative materials. In place of cedar wood, other woods have been substituted but these are generally conceded to be inferior .-to cedar. Attempts have also been made toprepare wrapped paper sheaths by laminating paper with various adhesives such as sodium silicate and thermosetting resins alone. The pencils made from sodium silicate have provedunsatisfactory when kept for long storage periods because they ,are sensitive to climatic changes, particularly humidity, and are difiicult to sharpen under high humidity conditions.

An object of this invention is to make composition pencils and pencil-like articles which will have tthe char- ,acteristic qualities generally associated with high-grade wood pencils such as strength, good sharpening, both by knife and by conventional pencil sharpeners, and high resistance to humidity.

Another object of this invention is to produce pencils from inexpensive and readily available materials.

Still another object is to produce zpencils by .a simple mechanical operation.

These .and other objects which will become apparent may be accomplished by the procedure-of the presentin- 'vention, which is described below.

Briefly the process of makingour pencils and pencil-like articles comprises enveloping .a core with paper which has-been coated or impregnated with a binder, shaping the resulting sheath if desired, and curing the binder. The articles may then be finished in the conventional manner by lacquering, stamping, applying ferrules, etc.

The binder consists of the reaction product of an adhesive and an embrittling agent .and, if desired, a lubricant, a perfume, and coloring material. It must be stable toward humidity changes so that the resultingimpregnated or coated sheath retains its physical properties over extensive temperature and humidity ranges.

The preferred adhesive is hide glue. Other water 'colloidally soluble protein materials, such as fish glue, also are satisfactory adhesives, although hydrated collagen (hide glue and gelatin) is preferred. Some proteins are better suited than others because of their solubility characteristics, their initial tack and adhesive qualities, but any water colloidally soluble protein may be employed if desired.

The embrittling agent serves to lessen the toughness of the adhesive and that section of paper or pulp coming in contact with the embrittling agent. This makes the formed sheath cut more readily and cleanly by the shearing forces of a pencil sharpener or knife. While watersoluble materials, which upon heating react with the adhesive and become converted into an insoluble form,

2,734,839 Patented Feb. 14, 1956 "ice 2 are generally satisfactory, and the low molecular weight formaldehyde condensates, such as those with phenol, furfuryl alcohol, urea, and melamine, and combinations of these, are typical examples of useful and preferred thermosetting resins or embrittlingagents, dimethylolurea has been found to be a most desirable thermosetting resin. These water-soluble materialsalso serve to render the composition less sensitive to humidity after reaction.

Theembrittling agent is referred to aboveas a thermosetting resin. The term thermosetting resin is intended to embrace materials such as dimethylol -urea which upon heating alone polymerizes to form a resin. In thepresent invention they also react with the adhesives to form the binder for the pencil sheath.

The adhesive must'be'tacky enough to hold the paper or pulp including the final lap, in the caseof a paper sheet, during and after the wrapping operation.

The lubricant may advantageously be calcium stearate or similar soap-like material. Waxes, preferably in the form of emulsions, may also be employed, aswell as unctuous minerals such astalc.

Many types of paper are suitable for this invention, but it is preferable to use a papersimilar to newsprint. It is desirable to incorporatesome heft, or sulfite Efiber, in thepaper when it is being,made:to give it additional strength.

The following description of the process, using :the preferred materials is as follows:

The binder comprised of'hide glueas the-adhesive, and dimethylolurea are the embrittling and stabilizing agent, is made upas a'water solution in equal parts and containsa small amount of dispersed calcium stearate as a lubricant. The concentration of materials in solution isv notcritica'l but should be as high as possible so that less water need be removed from the wrapped pencil. The concentration should be such as :to' give sufficient tack to the surface of the treated paper to preclude unwinding ordelaminating after forming :and before drying.

The binder solution is impregnated or coated on the paper. Although it is usually preferable to add the adhesive and the embrittling agent to the paper in :0118 solution as a one-step process, it is .possiblefirst to treat the paper with the embrittling agent and .then to wrap .the paper with adhesive into the desired pencil. The quantity of binder required for this operation may vary from 10 to 50% by weight of the paper and preferably 20-35% by weight.

Forming the pencil may be .accomplished by rolling the pencil lead up in treated paper until the desired size is reached, shaping the pencil as by putting it through a die to give it a hexagonal shape, drying the pencil either by heat or other-wise and with or without a .catalyst for the reaction, andfinishing, if desired, in the conventional manner. Economic advantages may be obtained by coating the tab end of the wrapping paper with a plastic or other finishing material so that, the finished article will have the tab on its .outer surface,'thus eliminating the necessity for lacquering.

The application .of the binding material and the rolling of the pencil may be done over a wide temperature range. It is preferable, .however, to carry out the wrapping operation at from v65--1 60 F. These temperatures allow the use :of higher concentration binders and the pencil results in being' introduced into the dryingpham'ber already preheated. The drying temperature is also not critical, the maximum temperature allowable being dependent upon the paper used and the temperature at which it deteriorates, but the preferred temperature range is from to 275 F. The length of the drying cycle depends upon the paper and temperature used and is usually about 4 hours at 212 R, if no catalysts are used.

The time may be shortened by use of catalysts, for instance diammonium hydrogen phosphate.

In the above description it was stated that the ratio of hide glue to dimethylolurea is preferably kept at approximately one to one by weight. However, it has been found satisfactory to use up to 7 parts by weight of hide glue to 3 parts by weight of dimethylolurea. A larger proportion of hide glue tends to make the resulting pencil sensitive to high humidity. On the other hand, it is possible to increase the proportion of dimethylolurea to a ratio of 1 part by weight of dextrine to 9 parts by weight of dimethylolurea. Larger propor tions of dimethylolurea do not permit proper adhesion particularly with respect to the final lap. As a matter of fact, substantially higher proportions of dimethylolurea may make the present simple wrapping process impractical, since the individual pencils would have to be held mechanically until the dimethylolurea was set to eliminate unwrapping.

In order to more fully understand the invention, the following example, illustrative of a successful method of accomplishing the objects above stated, is given:

The invention may be better understood by reference to the accompanying drawing wherein:

Fig. 1 is a coated paper, a pencil lead and a ferrule.

Fig. 2 is a partially rolled-up pencil.

Fig. 3 is a rolled-up pencil.

Fig. 4 is the pencil of Fig. 3 after passing through a die to form it into a hexagonal shape.

Fig. 5 is the pencil of Fig. 4 complete with ferrule and sharpened.

Fig. 6 is an eraser surrounded by a sheath similar to that of the pencil lead in Fig. 5.

Referring to the drawings more specifically, 11 is the base, such as paper, coated with a binder 12. Pencil lead is rolled up in the coated base to form a blank pencil having a nearly invisible lap 16. After passing pencil blank through a hexing die, ferrule 13 having an eraser 14 is attached. A lacquer 17 is applied to pencil 15. Fig. 6 refers specifically to an eraser. having a sheath 18 and an abrasive composition 19 located centrally within the sheath 18.

Example 36.3 g. hide glue 65.5 g. dimethylolurea (60% solids) 43.2 g. water.

The hide glue was dissoived in the water with gentle heating. The dimethylolurea was then added and dissolved with stirring. Calcium stearate was added and dispersed by means of a highspeed mixer such as a Waring Blender. The binder thus produced was coated on newsprint. The paper was wrapped convolutely around a lead after which the assembly was dried at 200 F. The resulting pencils sharpened easily and were characterized by having good resistance to high humidity.

In the foregoing description, reference was made to the binder comprising an adhesive and an embrittling agent. The heating of the embrittling agent causes a polymerization reaction to take'place. It is believed that the adhesive enters into this polymerization reaction since a product is formed from which the water soluble adhesive may not be extracted. In compatible systems such as the dimethylolurea-hide glue mixtures X-ray diffraction studies disclose that both the adhesive and embrittling agent when polymerized alone have a definite crystal structure. When heated together, the final product is amorphous. It is known that by using an embrittling 4 agent, the sheath may be readily sharpened, either by knife or by mechanical means, to form a smooth cut similar or superior, to that obtained by the finest straight grained pencil wood.

Extensive laboratory tests have shown that pencils made in accordance with the process herein described are strong, and have superior sharpening qualities as well as being relatively insensitive to humidity changes.

If is is desired, the paper used in wrapping the pencil may be dyed and perfumed a color and odor similar to that of cedar wood. When so treated, it is ditficult to distinguish a pencil made in accordance with this invention from that made from prime cedar wood.

Although the above example and description have been directed primarily to pencils, it is apparent that this invention is equally applicable to pencil-like articles such.

as crayons, erasers, eyebrow pencils, and similar structures. The appended claims are therefore intended to cover broadly such articles.

Having now described our invention we claim: 1. As an article of manufacture, a core, and a rigid sheath surrounding said core, said sheath comprising paper tightly wound upon said core, and bonded together and to'said core by a binder and heat cured at a temperature between ambient and about 275 F., said binder preventing delamination and consisting essentially of dimethylol urea and a water colloidally soluble protein selected from the group consisting of hide glue, fish glue, and gelatine, said protein and said dimethylol urea being present in a weight ratio of between 7:3 and 1:9, said sheath being substantially unaffected by humidity.

2. An article of manufacture in accordance with claim 1, wherein said protein is hide glue.

3. -An article of manufacture in accordance with claim 1, wherein said protein is fish glue.

4. An article of manufacture in accordance with claim 1, wherein said protein is gelatine.

5. An article of manufacture in accordance with claim 1, wherein said binder contains a lubricant.

6. The process of forming a rigid sheath about a core, which comprises applying to a paper sheet a binder consisting essentially of a water colloidally soluble protein selected from the group consisting of hide glue, fish glue, and gelatine, and dimethylol urea, in a weight ratio of between 7:3 and 1:9, wrapping the thus-treated paper tightly around said core to form said sheath thereabout, and heating the resulting structure at a temperature between ambient and about 275 F. sufiicient to cause said protein and said dimethylol urea to form a reaction product which is substantially unaffected by humidity and which bonds the convolutions of said sheath firmly together against delamination and which also bonds said sheath to said core.

References Cited in the file of this patent UNITED STATES PATENTS 444,233 Denney Jan. 6, 1891 477,593 Greenfield June 21, 1892 600,745 Sands Mar. 15, 1898 679,264 Pedley July 23, 1901 1,222,152 Smith Apr. 10, 1917 2,133,335 Wilson et a1 Oct. 18, 1938 2,323,831 Menger et a1 July 6, 1943 2,510,941 Ake et al. June 13, 1950 FOREIGN PATENTS 16,194 Great Britain of 1898 

1. AS AN ARTICLE OF MANUFACTURE, A CORE, AND A RIGID SHEATH SURROUNDING SAID CORE, SAID SHEATH COMPRISING PAPER TIGHTLY WOUND UPON SAID CORE, AND BONDED TOGETHER AND TO SAID CORE BY A BINDER AND HEAT CURED AT A TEMPERATURE BETWEEN AMBIENT AND ABOUT 275* C., SAID BINDER PREVENTING DELAMINATION AND CONSISTING ESSENTIALLY OF DIMETHYLOL UREA AND A WATER COLLOIDALLY SOLUBLE PROTEIN SELECTED FROM THE GROUP CONSISTING OF HIDE GLUE, FISH FLUE, AND GELATINE, SAID PROTEIN AND SAID DIMETHYLOL UREA BEING PRESENT IN A WEIGHT REATIO OF BETWEEN 7:3 AND 1:9, SAID SHEATH BEING SUBSTANTIALLY UNAFFECTED BY HUMIDITY.
 6. THE PROCESS OF FORMING A RIGID SHEATH ABOUT A CORE, WHICH COMPRISES APPLYING TO A PAPER SHEET A BINDER CONSISTING ESSENTIALLY OF A WATER COLLOIDALLY SOLUBLE PROTEIN SELECTED FROM THE GROUP CONSISTING OF HIDE GLUE, FISH GLUE, AND GELATINE, 2ND DIMETHYLOL UREA, IN A WEIGHT RATIO OF BETWEEN 7:3 AND 1:9, WRAPPING THE THUS-TREATED PAPER TIGHTLY AROUND SAID CORE TO FORM SAID SHEATH THEREABOUT, AND HEATING THE RESULTING STRUCTURE AT A TEMPERATURE BETWEEN AMBIENT AND ABOUT 275* F. SUFFICIENT TO CAUSE SAID PROTEIN AND SAID DIMETHYLOL UREA TO FORM A REACTION PRODUCT WHICH IS SUBSTANTIALLY UNAFFECTED BY HUMIDITY AND WHICH BONDS THE CONVOLUTIONS OF SAID SHEATH FIRMLY TOGETHER AGAINST DELAMINATION AND SHICH ALSO BONDS SAID SHEATH TO SAID CORE. 